Harry Potter and the Methods of Rationality

[BabylonHoruv]

Also, finally noticing a bias I had, yet another option is that squibness is a recessive trait in wizards that occasionally comes out.  Perhaps a vestigial trait on its' way out, after a several wizard generations.

Yeah, that was what I was suggesting with the 6 of them means no magic.  Squibs seem to appear more often in pureblood families than otherwise, as far as I can tell.

[Don Coyote]

Also, finally noticing a bias I had, yet another option is that squibness is a recessive trait in wizards that occasionally comes out.  Perhaps a vestigial trait on its' way out, after a several wizard generations.

Yeah, that was what I was suggesting with the 6 of them means no magic.  Squibs seem to appear more often in pureblood families than otherwise, as far as I can tell.

http://www.thetech.org/genetics/ask.php?id=29

About the crazy genetics of human eye color. it may be pertinent.

[Juana]

That's pretty cool! Explains why my hazel and blue eyed parents only produced one blue eyed child (the other one and I are hazel and green respectively).

The other possibility is that wizarding isn't genetic.  Magic has so far failed to follow any other sensible rules, so why this?

Magic may not be tied directly to DNA in Rowlings universe, however it does have a MUCH higher incidence of appearance in children of witches and wizards than in children of muggles.  So wether or not it is genetic it is hereditary.

It could be genetic and rely on more than 2 bits, so, for instance, say it relies on 6 bits, if someone has 1 or 2 of those bits they have no magic, if they have 3,4,or 5 they have magic, if they have 6 they have no magic.  I don't know if real genes can work that way but it would allow for both muggle borns and squibs if it worked that way.

It is. As I recall, she mentioned in an interview somewhere that the magical gene is dominant.

[Requia ☣]

Then where do muggle borns come from?

[Juana]

Then where do muggle borns come from?

In a different interview, she confirmed the fandom speculation that they're the descendants of squibs (a character who preceded Rita Skeeter as a foil for Hermione was a cousin of the Weasleys but technically speaking a muggleborn, since she's the child of Molly's squib brother who left for the muggle world). I'm guessing something in the environment maybe turns the gene(s) back on?

[Cain]

I think Rowling

a) sucks at genetics
b) made up most of the Harry Potter world as she went along, with little consideration for consistency or logic

[BabylonHoruv]

I think Rowling

a) sucks at genetics
b) made up most of the Harry Potter world as she went along, with little consideration for consistency or logic

Absolutely.  But the author of  this particular fanfic is trying to impose sense on it all.

Also, although Rowling paid very little attention to logic or science she did incorporate an awful lot of mythology, in fairly accurate ways.  Her world is fairly consistent, it's just not consistent with our world.

[Kai]

I did find a logical fallacy however.  The theory of magical genetics that Harry and Draco work out doesn't work.  It explains muggleborns but it does not explain squibs.  If magic is a simple Mendelian recessive trait than any two wizards have to have a wizard child, they can't have a squib as a child.

think wizard; Ww or WW

squib ww

sence?

squibs are basically muggles in effect, with an awareness of magic.  may be attributed to other factors

No.

Wizard: WW
Squib: Ww
Muggle: ww

A wizard must have two copies of the same gene. The effect must be that two squibs will produce 1/4 wizards. A squib is simply a name for a non-magical person who comes from two wizards. A muggle could technically be a squib and not know it, thus allowing people like Hermoine to be a witch (WW) yet have muggle (squib) parents (Ww).

You can make a Mendelian crossing diagram like so
              W              w
W        WW          Ww

w         wW           ww


This of course creates a problem, UNLESS you allow for mutation. Consider that the w is an inoperable allele. Therefore, in a wizard family where both parents have WW you could STILL get squibs, if there is a mutation at the W locus that causes it to be inoperable. This would have to be as a result of base pair changes during crossing over or meiosis. From what I gather, a squib is a rare event in families where both parents are wizards. How would it look if one parent was a complete muggle and the other a wizard?

           w              w
W     Ww         Ww

W    Ww         Ww

That would me that with a WWxWw cross, none of their children would be wizards (all squib) but one fourth of their childrens children would be wizards.



Unless I'm completely wrong and the wizard gene is recessive rather than dominant. In that case, it looks completely the same except the W allele inhibits the w allele. That almost makes more sense. Maybe some incomplete dominance going on too.

[Requia ☣]

I think its incomplete dominance (for the purpose of the fanfic), which is why squibs can see all the magic stuff, but not actually use it the same way wizards do.

So with a WW (wizard) and Ww (squib) cross, half the kids would be wizards and half squibs.

Though, if we're going to try and poke at Harry's science, I'd point out that he might be wrong about it being genetic altogether.  IE, magical ability could be determined by environmental conditions.  Squibs could in turn have a dominant mutation that inhibits magical ability, which would provide the same number of wizard offspring from squib couples, as long as none of the squibs involved have a double dose of the dominant gene.  Easy to check too, just ask the paintings how many of the squib couples earlier mentioned had muggle children.

[BabylonHoruv]

I think its incomplete dominance (for the purpose of the fanfic), which is why squibs can see all the magic stuff, but not actually use it the same way wizards do.

So with a WW (wizard) and Ww (squib) cross, half the kids would be wizards and half squibs.

Though, if we're going to try and poke at Harry's science, I'd point out that he might be wrong about it being genetic altogether.  IE, magical ability could be determined by environmental conditions.  Squibs could in turn have a dominant mutation that inhibits magical ability, which would provide the same number of wizard offspring from squib couples, as long as none of the squibs involved have a double dose of the dominant gene.  Easy to check too, just ask the paintings how many of the squib couples earlier mentioned had muggle children.

There's no real way to tell a muggle from a squib. 

[Requia ☣]

A squib can see a dementor, a muggle cannot.  Presumably squibs have other awareness of magic that muggles do not.

[BabylonHoruv]

A squib can see a dementor, a muggle cannot.  Presumably squibs have other awareness of magic that muggles do not.

heh, that would be a fun test.  I bet Draco would enjoy applying it to Hermione's parents.

[Kai]

A squib can see a dementor, a muggle cannot.  Presumably squibs have other awareness of magic that muggles do not.

heh, that would be a fun test.  I bet Draco would enjoy applying it to Hermione's parents.

That would have a pretty clear conclusion too. Either they can see it, or not. If they can, it further supports the wizarding allele hypothesis. If not, it falsifies the hypothesis.

[Pope Lecherous]

A squib can see a dementor, a muggle cannot.  Presumably squibs have other awareness of magic that muggles do not.

heh, that would be a fun test.  I bet Draco would enjoy applying it to Hermione's parents.

That would have a pretty clear conclusion too. Either they can see it, or not. If they can, it further supports the wizarding allele hypothesis. If not, it falsifies the hypothesis.

people need to get laid ITT 

[Kai]

A squib can see a dementor, a muggle cannot.  Presumably squibs have other awareness of magic that muggles do not.

heh, that would be a fun test.  I bet Draco would enjoy applying it to Hermione's parents.

That would have a pretty clear conclusion too. Either they can see it, or not. If they can, it further supports the wizarding allele hypothesis. If not, it falsifies the hypothesis.

people need to get laid ITT 

Excuse me, virgin. Girlfriend = pornstar. IOW, enjoy your sock.